50% off due to medical reasons? And how has that got anything to do with gender?
If you want to look at it statistically, I can give you some examples from my own company/ base.
15% are female.
Of the 85% who are male, 17% of the (male) FOs have been off sick so often its become a standing joke (and they've been interviewed for the high sickness level). 13% of the Captains have had at least 6 months off in the past year due to medical reasons. Another 26% have been off for a considerable period in the past year or two.
Of course then there is the 0.6% of pilots who used to be male and are now female. Which camp would you like the put them in? The "fight and survive" (or perhaps crash and burn, which is the flipside of this response) or the "cry lots" camp (actually women go more for the think rather than act, and can actually use intellect to get out of a situation rather than piling in straight away and attempting to use bravado. Kind of reminds me of the Azores glider incident, can't think why....).
Of the 15% of female pilots, their sickness record is at least as good as the male pilots.